CMOS image sensors (CISs) are commonly used in consumer electronics products, such as digital still cameras, video recorders and photo-capable mobile terminals. In a typical device, an array of CISs are used to capture light energy and output corresponding electrical signals, with each sensor typically corresponding to a pixel of an image. Typically, a CIS only discriminates light intensity information. In order to provide color discrimination, color filters are typically arranged over the sensor array to filter particular color components of the light so that individual sensors may provide color component information.
In order to produce high definition images, CISs generally need to be reduced in size such that a larger number of sensors may be employed in a given area. However, increasing sensor integration density may cause an increase in crosstalk among the sensors, which may cause a lowering of sensitivity. Crosstalk between sensors having different color filters may result in spectral distortion in individual sensor outputs, and may cause a decrease in signal-to-noise ratio (SNR) and color reproducibility.
Conventional techniques for compensating for crosstalk include amplifying the sensor output signal and/or using a color correction circuit to correct for the crosstalk. Such approaches may be limited due to increased noise and problems with color reproducibility.
Typical conventional imaging devices employ color interpolation. In a typical color interpolation process, signals from multiple adjacent pixels are combined to generate appropriate color information for a given pixel. For example, signals from adjacent red and green pixel sensors may be used to generate interpolated green and red signals for a blue pixel. Color interpolation may, however, introduce false color errors. A conventional approach to correcting false color error is to insert an optical low pass filter (OLPF) between each sensor and the lens from which it receives incident light.